Multi-color printing on continuous metal bands



Jan. 31, 1961 MULTI- A. v. BORCH-MADSEN 2,969,733 COLOR PRINTING ON CONTINUOUS METAL BANDS Filed Sept. 16. 1957 MULTI-COLOR PRINTING N CONTINUOUS METAL BANDS Andreas Vilhelm Borch-Madsen, 16 Lavendelstraede, Copenhagen, Denmark Filed Sept. 16, 1957, Ser. No. 684,052

Claims priority, application Denmark Sept. 26, 1956 6 Claims. (Cl. 101-181) This invention relates to multi-color printing and more particularly to multi-color printing on continuously moving metal bands, such as used in the canning industry for making cans or other containers of metal plate, in particular aluminium plate and provided at one or both surfaces with a multi-color pattern or design.

The method used in such printing processes is similar to that used for multi-color printing on continuous paper bands or webs. When providing a continuous paper band with a multi-color printing, the band is fed continuously through a series of printing stations, each of which imprints a pattern or design on the paper surface in one particular color, and these designs are subsequently superimposed upon one another by feeding the band through consecutive printing stations.

However, when adapting this well-known multi-color printing process to continuous metal bands, one is faced with two problems:

First.-Metal bands of the thickness normally used for the manufacture of cans or containers, i.e. above 0.1 millimeter, are made in rolling mills, and the mechanical stresses originating from this treatment are unevenly distributed over the surface of the finished band. Owing to these inherent stresses the band will have a tendency to be distorted when fed continuously through a printing machine whereby the correct register in the consecutive printing stations is impeded.

Second.Due to the fact that the dyestuffs, imprinted on the continuously moving metal band at each of the printing stations, cannot be absorbed in the band, special precautions must be taken for drying the dyestuffs between each pair of consecutive printing stations. This drying process is preferably made by subjecting the band to heating by passing it over heating drums intermediate each pair of consecutive printing stations. When using special kinds of printing dyestuffs, however, such heating drums may be omitted when precautions are taken to allow the dyestuffs to evaporate before the part of the band, on which the pattern has been imprinted in one station, is fed into the consecutive printing station. In both cases, however, the drying of the dyestuffs is inevitably accompanied by temperature variations, which will adversely affect the correct feeding of the hand through the consecutive printing stations and give rise to lengthwise or sidewards displacements of the band relatively to the printing rollers in the consecutive printing stations, whereby the correct register of the superimposed patterns constituting the multi-color design is prevented.

The lengthwise and sidewards displacements of the band are caused by the change of temperature conditions at various points of the printing machine due to the heating or cooling of the band as a consequence of the drying operation. These temperature variations will cause expansion or shrinkage of the band resulting in a distortion at various intervals of the continuously moving band, the ultimate result being an oblique course of the band when passing through the printing stations.

Patented Jan. 31, 1961 "ice For these reasons it has been found practically impossible to adapt the well-known multi-color printing methods used in printing on continuously moving paper or textile bands to metal bands, and multi-color printing on metal for making cans or containers has therefore so far been confined to printing on metal sheets.

Although this method is quite satisfactory as far as the actual multi-color printing is concerned, it will inevitably involve a considerable waste of material due to the fact that each sheet will have to be cut off at the edges before it can be used for the manufacture of cans or containers. When the patterns are of square or rectangular shape the waste may be reduced to a minimum by cutting the band close to the contours of the patterns. On the other hand, when the patterns are of round or irregular shape and arranged so as to fill up the available surface area, it is inevitable that a number of these patterns are cut through, which will result in a waste of material.

From an economical point of view it is therefore desirable to use continuous metal bands so as to avoid waste of material and to speed up the printing operation.

The present invention is therefore concerned with the simultaneous solution of the two problems which are inseparably associated with the continuous feeding of a metal band of the thickness normally required for the manufacture of cans or containers but which do not arise in the printing of continuous paper or textile webs having a porous surface capable of absorbing the dyestuffs and having no initial stresses which adversely affect the feeding operation.

The particular object of this invention is therefore to provide a method of controlling the movement of a continuously moving metal band in a multi-color printing process, wherein the band is passed through a series of printing stations provided with color-drying arrangements whereby the metal band is subjected to temperature variations, the method being carried out in such a manner that the effect of the above mentioned thermomechanical phenomenae which adversely affect the printing operation is eliminated.

According to the invention these problems are solved by controlling the movement of the continuous metal hand through the printing machine in the following manner:

First, the band is fed through a perforating machine, wherein the band is provided with perforations along either edge thereof.

Secondly, the perforated band is passed through a first printing station comprising a printing roller and a supporting roller associated therewith and a pair of sprocket rollers at either side of the printing roller arranged so as to engage the perforations in the band and to hold the band tightly against the surface of the printing roller during the printing operation.

Thirdly, when leaving the first printing station, the band is passed over a pair of interspaced guide rollers so arranged as to cause the band to hang in a loose loop of sufiicient length and width to allow for distortions in the band along the interval defined by the loop, so as to eliminate the effect of the initial stresses and temperature variations before passing the band on to the consecutive printing station.

The same operation, comprising the formation ofstress compensating loops between each pair of consecutive printing stations, is repeated throughout the printing operation until the band is finally wound up on magazine drums at the rear end of the printing machine.

As an intermediary stage, which is normally required when working with dyestuffs requiring a special drying process, the band is passed over a drying drum which is printing station above the printing roller, before the band is fed on to the loop-forming guide rollers between a pair of consecutive printing stations.

In one particulm embodiment of the invention, a fur ther stage of the operation may be introduced between the formation of the compensating loop and the feeding into the subsequent printing station, said stage comprising subjecting the band to cooling to a predetermined temperature before being fed into the said printing station.

In this manner, the band will always be maintained at an adequate temperature suitable for ascertaining complete elimination of any remaining stresses in the band before it is introduced into the printing stations.

The essential features and advantages of the invention will now be explained with reference to the accompanying drawings, in which:

Figure 1 schematically illustrates a side view of a multicolor printing machine including three printing stations, and

Figure 2 is a section taken along line IIII in Figure 1.

Referring to the drawings, the continuous movement of a metal band 19 through a printing machine comprises a frame 1 and three printing stations A, B and C, a. supply unit D at the front end and a take-up unit E at the rear end of the machine is controlled in the following manner:

The band It is drawn off a supply drum 2 and passed over a pair of feeding rollers 4, one of which is power driven as indicated by the arrow and is passed on to a perforating machine 5 of any conventional type located at the rear end of the supply unit D. Here the band is provided with two parallel rows of perforations along either edges and is passed on in a loop ltlDA between the unit D and the first printing station A.

The three printing stations A, B and C are identical and comprise the following components:

A printing roller 6 and a supporting roller 7 associated therewith for pressing the band firmly against the surface of the printing roller 6. A pair of sprocket rollers and 9 at either side of the printing roller and adapted to engage the perforations in the band so as to guide; move and stretch the band therebetween. A drying drum 20 located above the printing roller. This drum is preferably heated in any conventional manner and may be provided with lengthwise extending ribs or the like 21 for providing an airgap between the band and the heated surface of the drum 20. Finally, the printing stations are provided with a plurality of guide rollers, some of which are power driven as indicated by the arrows:

A front input roller 11. A front output roller 12. A front top roller 13. A rear top roller 14. A rear input roller 15. A rear output roller 16. Rollers 11 and are disposed on moveable arms for the reasons explained below.

Unit B is provided with a pair of feeding rollers 4 similar to those of the supply unit D and a magazine drum 3 for winding up the multi-color printed band at the rear end of the machine.

With the general arrangement of the machine as illustrated in Figure 1 the operation, when feeding the band 10 through the machine, is as follows:

In stations A and B the band 10 is passed over input roller 11, beneath sprocket 8, between rollers 6 and 7, beneath sprocket 9, over drum 20, beneath output roller 12 and over top rollers 13 and 14.

Top roller 14 of station A and input roller 11 of station B define a compensating loop ltlAB, the function of which has been explained in detail above. It will be observed that, in the printing stations A and B, the printing rollers 6 will print at the same side of the band 10. If, on the other hand, it is desired to print on the reverse side of the band, the passage of the latter through the printing station must be reversed as illustrated at station C. Here the band is fed into the printing station over the rear input roller 15 which is then swung out into its operating position, as shown at the rear of station C,

the front input roller 11 being simultaneously swung into its inoperative position, as shown at the front end of station C. The compensating loop ltlBC of the band 10 between stations B and C is thus formed between rollers 14 and i5, and after having passed over the drying drum 20 in station C the band is passed out of station C beneath output roller 16 at the rear end thereof, above top roller 14 and finally through feeding rollers 4 in unit E to the wind-up drum 3 at the rear end thereof. It will be noticed that roller 16 is inoperative in stations A and B.

For the reasons previously explained, the band may be subjected to cooling to a predetermined temperature prior to being fed into the printing stations. Such cooling may conveniently be effected by maintaining one of the loop forming rollers, preferably the front input roller 11 at a predetermined lower temperature than the temperature of the band in the preceding interval thereof. The cooling and the maintenance of the temperature of this roller may be made in any conventional manner, e.g. by passing a thermo-statically controlled cooling liquid through a cavity within the roller.

I claim:

1. The method of controlling the movement of a continuously moving heat-expansible metal hand during printing thereof in a continuous multi-color printing process, wherein the band is passed through a series of consecutive printing stations, said method comprising the steps of (a) passing the band with continuous movement through a perforating machine, so as to provide the moving band with perforations along either edge thereof,

(b) thereafter passing the moving perforated band through a first printing station comprising a printing roller and a pair of sprocket rollers arranged at either side thereof, so as to engage the sprocket rollers with the perforations and thereby to hold the band tightly against the surface of the printing roller by the sprocket rollers during the printing operation, thereafter while the band is moving (0) compensating for distortions of the band set up by inherent stresses in the band due to changes in the temperature of the band accompanying the rapid evaporation of the imprint on the band by passing the band with a continuous movement during such temperature changes over a pair of interspaced guide rollers arranged so as to cause the band to hang in a loose loop between said guide rollers as it changes temperature and before passing the band on to a consecutive printing station, and

(d) passing the imprinted band having the dried imprint through a second printing station comprising a printing roller and a pair of sprocket rollers arranged at either side thereof to engage the band perforations and effect a positive feed of the band at the same rate and with a continuous movement through the said second printing station.

2. The method of controlling the movement of a continuously moving heat-expansible metal hand during printing thereof in a continuous multi-color printing process, wherein the band is passed through a series of printing stations provided with color drying arrangements, whereby the metal band is subjected to temperature variations, said method comprising the steps of (a) passing the band with continuous movement through a perforating machine, so as to provide the moving band with perforations along either edge thereof,

(b) thereafter passing the moving perforated hand through a first printing station comprising a printing roller and a pair of sprocket rollers arranged at either side thereof so as to engage the sprocket rollers with the perforations and thereby to hold the band tightly against the surface of the printing roller by the sprocket rollers during the printing operation, thereafter (0) passing the band while continuously moving over a drying roller Where the surface of the band is subjected to temperature variations, and thereafter while the band is moving (a') compensating for the distortions of the band set up in the band by said temperature variations by passing the band with a continuous movement over a pair of interspaced guide rollers arranged so as to cause the band to hang in a loose loop between said guide rollers as it changes temperature and before passing the band on to a subsequent printing station, and

(e) passing the imprinted band having the dried imprint through a second printing station comprising a printing roller and a pair of sprocket rollers arranged at either side thereof to engage the band perforations and effect a positive feed of the band at the same rate and with a continuous movement through the said second printing station 3. A method as defined in claim 2, in Which the band is subjected to a heating and drying process immediately after each of the two printings and wherein the band after each such heating and drying is subsequently subjected to cooling to predetermined temperature, before being passed on to the consecutive printing station.

4. A machine for continuously multi-color printing on continuous heat-expansible metal bands comprising a series of printing stations through which the band is fed at equal rates of speed, each comprising a printing roller, a supporting roller associated therewith, and means comprising a pair of sprocket feed rollers disposed one at each side of the associated printing and supporting rollers for holding the bands tightly stretched at, ahead of, and beyond the said printing and supporting rollers, a

perforating machine arranged at one end of said printing machine for perforating said bands, said sprocket rollers being adapted to engage the perforations of the bands, a plurality of guide rollers disposed at either end of each printing station, at least two of said guide rollers being arranged so as to define a loose cooling and imprintevaporating loop of a continuous metal band as it is continuously fed through said printing machine over the guiding rollers intermediate a pair of consecutive printing stations whereby the expansion and/or contraction of the metal band due to temperature changes will not effect the said sprocket feed rollers and feed of the band through the printing stations.

5. A machine as claimed in claim 4, in which at least one of the said loop defining rollers is provided with cooling means for maintaining the temperature of said guide roller at a predetermined value.

6. A printing machine as claimed in claim 4, in which drying cylinders are disposed above the printing roller in each printing station, said drying cylinders being provided with lengthwise extending ribs, so as to provide an airgap between a band passing over the drying cylinder and the surface thereof.

References Cited in the file of this patent UNITED STATES PATENTS 1,784,037 Wolf Dec. 9, 1930 1,931,468 Bergholtz Oct. 17, 1933 2,037,091 Rosenthal Apr. 14, 1936 2,083,370 Greulich June 8, 1937 2,322,530 MacArthur June 22, 1943 2,338,143 Taylerson Jan. 4, 1944 2,494,402 Mursch Jan. 10, 1950 2,722,630 Share Dec. 4, 1956 2,773,688 Fulk Dec. 11, 1956 2,800,327 Bandy July 23, 1957 

